Wet spinning process and apparatus



Feb. 3, 1959 'c. E. PAGE EI'AL 2,871,512

WET SPINNING PROCESS AND APPARATUS Filed June 10, 1955 C '15- PAGE I DOWN/N6 I M/vtwaxs United States Patent WET SPINNING PROCESS AND APPARATUS Cliiford Ernest Page and John Downing, Spondon, near Derby, England, assignor to British Celanese Limited, a corporation of Great Britain Application June 10, 1955, Serial No. 514,617

Claims priority, application Great Britain June 18, 1954 3 Claims. (Cl. 18--8) This invention relates to the manufacture of artificial filamentary materials by a downward wet spinning process. 1

In one method of making artificial filamentary materials a spinning solution is extruded through a downwardly facing spinning jet, and the filaments formed travel downwardly in a co-current stream of coagulant through a vertical spinning funnel or tube, hereinafter and in the claims referred to simply as a spinning tube, with a restricted opening at its lower end. After leaving the tube through this opening, the filaments are drawn aside as a bundle or yarn out of the path of the coagulant, which continues in its vertical path until it reaches a funnel or other collecting means. Thus, the yarn may be drawn laterally, horizontally or at an angle to the horizontal, by a godet or the like and passed to a washing device, for example as described in U. S. application S. No. 510,754, filed May 24, 1955, now abandoned.

We have found that when working in this way, breakage-of any single filament generally results in that part of the filament which is behind the break being carried on in the stream or jet of coagulant and not rejoining the main filament bundle or yarn unless replaced on the godet by hand.

We have also found that this difficulty can be largely or completely overcome by providing, below and near to the open lower end of the spinning tube, a plate which slopes downwardly in the lateral direction in which the filamentary material is drawn aside out of the stream of coagulant.

The invention therefore comprises a wet spinning device adapted for downward spinning, comprising a spinning tube having an orifice at its lower end for the passage of filamentary material and coagulant from the tube, means for drawing the filamentary material laterally from the said orifice, and a plate below and closely spaced from the said orifice, and set or capable of being set at a downward inclination in the lateral direction of travel of the filamentary material from the orifice. Preferably the distance from the orifice to that part of the plate which is vertically below it is not more than 1 inch, for example between A and 1 inch and especially between A and /2 inch.

The invention comprises also a process for the manufacture of artificial filamentary material by a wet spinning method, in which the filamentary material and a coagulant travel together downwardly through a spinning tube and leave it by an orifice at its lower end, the filamentary material is drawn aside from the stream of coagulant emerging from the orifice, and the stream of coagulant is caused to impinge on a solid surface below and closely spaced from the orifice and inclined downwardly in the lateral direction in which the filamentary material is drawn from the orifice.

As indicated above, the advantage of the use of the plate in the applicants wet spinning device is that, in the event of a filament breaking, that part of the filament "ice which is behind the break is not carried on with the coagulant travelling down the plate, but is caught up with the travelling unbroken filamentary material. It appears that the effectiveness of the plate for this purpose depends not only on the fact that it breaks up and diverts from its. vertical path the stream or jet of coagulant issuing from the orifice at the bottom of the spinning tube, but also on the diminution in the linear speed of the coagulant caused by the spreading out of the stream over the surface of the plate. This view is supported by the observation that, for a given effect, the greater the volume rate of flow of coagulant down the spinning tube, the wider should be the plate, or the smaller the angle to the horizontal at which it is set.

it is thus not possible to give figures for the dimensions of the plate or its angle to the horizontal which will givethe best results under all circumstances, though a suitable angle and dimensions can very easily be found by test for any particular case. As a general rule, when yarns of fairly low denier are being spun, the plate may I measure about 2-3 inches along the line of slope and about 1-3 inches across it, and be set at an angle between about 3 and 30, and especially between about 5 and 15, to the horizontal. When yarns of higher denier are being made, especially materials of denier 1500-2000 or more such as may be used in the production of staple fibre, the best results may be obtained when the plate is somewhat wider and/or its angle of slope is smaller. Advantageously the plate is provided with a low wall along its upper edge and its two sides, so as to lead all the coagulant down the plate and prevent any falling over the sides or the upper edge. The wall may for example be about /2 inch high.

If desired the plate may be mounted on a movable arm or bracket so that it can be swung out of position to allow easy access to the lowerend of the spinning tube when starting up. It is advantageous also that it should be so mounted that its slope can easily be altered during spinning; thus it may be pivoted vertically below the open end of the spinning tube sutficiently stiflly to hold any position in which it may be placed.

While the invention is generally applicable to the manufacture of filamentary materials by wet spinning methods in which the material and coagulant travel together down, a vertical or nearly vertical spinning tube, it is particularly valuable in connection with the manufacture of cellulose acetate materials by extruding an acetone so.- lution of cellulose acetate intoaqueous acetone or aqueous diethylene glycol diacetate, for example as described in U. S. applications S. Nos. 323,788, filed December 12, 1952 and S. No. 510,754, filed May 24, 1955. It may however, be applied to other wet spinning processes, e. g. to the spinning of acetic acid solutions of cellulose acetate into aqueous acetic acid, which may contain a high concentration of salt, e. g. an alkali metal acetate, or into water containing a high concentration of salt. Solutions of substances other than cellulose acetate may also be spun in accordance with the invention. Such substances include other esters of cellulose, especially cellulose esters of lower fatty acids such as propionic and butyric acids, and synthetic polymers such for example as polymers and copolymers of acrylonitrile, vinyl chloride and other vinyl compounds. The invention may also be applied to the spinning of viscose and cuprammonium solutions.

The invention is illustrated in the accompanying drawing, in which,

Figure 1 is a side view of part of a wet spinning device, and

Figure 2 is a section taken on the line 2-2 in Figure 1.

Referring now to the drawing, the wet spinning device comprises a spinning tube 3, of which only the lower end is shown, terminating in a restricted orifice 4 having a smooth rounded edge. A yarn 5 formed in the device and coagulant flow down the spinning tube 3 together and leave it through the orifice 4, the yarn being at once drawn horizontally to one side by a godet 17 of conventional design.

A bracket 6 is mounted on the spinning tube 3 by means of nuts and bolts 7, and comprises a reversed angle section 8 extending laterally to a distance greater than the radius of the spinning tube 3 (Figure 2). An L-shaped member 9 is pivotally mounted at the end of the bracket 6 and can be fixed in any desired position by means of a l-Il locking wing-nut 10. A plate 11 is pivotally mounted by means of downwardly extending brackets 12 on the other arm of the L-shaped member 9 and is held by means of a nut 13 and a spring washer 14 with a degree of stiffness such that, while it can be adjusted by hand, it will then retain its position under operating conditions. The relative dimensions of the member 9 and the brackets 12 are such that the upper surface of the plate 11 is A to 1 inch below the orifice 4, and the bracket 6, and thus the member 9, are so positioned that the plate 11 is held with its longer sides parallel to the lateral direction of travel of the yarn 5 from the orifice 4. Except along its lower edge 15 (i. e. the end below the traveling yarn 5), the plate 11 is provided with a low wall 16.

In operation the plate 11 is so fixed that it slopes downwards in the lateral direction of travel of the yarn 5 at a suitable angle which will vary with different spinning conditions as described above. The stream of coagulant leaving the spinning tube 3 by the orifice 4 almost at once impinges on the plate 11, down which it flows until it reaches the lower edge 15, whence it falls into any suitable collecting means. The yarn meanwhile. is drawn horizontally away from the orifice 4 round the edge thereof. If any filaments break, it is found that the broken ends do not remain in the coagulant stream, but are picked up and carried along by the unbroken yarn.

Having described our invention, what we desire to se cure by Letters Patent is:

I. A wet spinning device for downward spinning, comprising a substantially vertical spinning tube having an orifice at its lower end for the passage of filamentary material and coagulantfrom the tube, means for drawing filamentary material laterally from the said orifice, and

a plate pivotally mounted below the said orifice, said plate in operative position sloping downwardly at an angle of 330 to the horizontal in the same lateral direction as that in which the said drawing means lies in relation to the orifice, that part of its surface which is directly below the orifice being spaced between A inch and 1 inch therefrom.

2. A wet spinning device for downward spinning, comprising a substantially vertical spinning tube having an orifice at its lower end for the passage of filamentary material and coagulant from the tube, means for drawing filamentary material laterally from the said orifice, and a plate pivotally mounted on a bracket Which is in turn pivotally mounted, the arrangement being such that by means of the bracket mounting the plate can be moved between an operative position below the orifice and a stand-by position to" one side of the spinning tube and by means of the plate mounting it can be set to slope downwardly at an angle of 33'() to the horizontal in the same lateral direction as that in which the said drawing means lies in relation to the orifice, and that when the plate is in its operative position that part of its surface which is directly below the orifice is spaced between A inch and 1 inch therefrom, the pivotal mounting of the plate being free enough to allow the inclination of the plate to be adjusted by hand, and stiff enough to maintain the inclination constant under the impact of liquid from the spinning tube thereof.

3. Process for the manufacture of artificial filamentary material by wet spinning, which includes the steps of extruding a solution of cellulose acetate into a coagulating bath causing the resulting freshly formed filamentary material and the coagulant to travel togetherdownwardly through a substantially vertical spinning tube and to leave it by an orifice at its lower end, drawing the filamentary material laterally from the said orifice and out of the stream of coagulant emerging from the orifice, and at a distance of inch-1' inch below the orifice reducing the velocity of the said stream by deflecting it in the lateral direction in which the filamentary material is drawn from the orifice and at a downward inclination of 3-30 to the horizontal, while simultaneously causing it to spread out over a solid surface.

References Cited in the file of this patent UNITED STATES PATENTS 1,683,478 Neidich Sept. 4, 1928 2,251,247 Bauriedel July 29, 1941 FOREIGN PATENTS 290,560 Great Britain June 28, 1928 

